With their numerous excellent characteristics, numerous blow molded bottles, in particular, bottles (so-called pet bottles) that are made of polyethylene terephthalate (PET) resin and molded by biaxial stretch blow molding are heavily used as bottle containers in a variety of fields.
Containers of such a kind are generally molded with use of a preform that has been inject-molded into a bottomed tubular shape like a test tube. In a state where the preform is heated to a temperature at which a stretching effect is achieved, the preform is vertically stretched in an axis direction by means of a stretching rod and is inflated and stretched by means of blow air injected into the preform through a blow nozzle fitted tightly to a mouth tubular portion of the preform.
On the other hand, Patent Literature 1 describes an invention directed to a method for molding a plastic bottle in which a preform is blow molded by means of a liquid supplied as the pressure medium through the blow nozzle instead of air. According to the blow molding method described in Patent Literature 1, when the liquid used as the pressure medium is water, tea, or a refreshing drink that is to be filled in the bottle as the product, the process of filling the liquid product may be omitted, and a production line may be simplified.